[PATCH] permission checks for chdir need special treatment only on the last step

... so we ought to pass MAY_CHDIR to vfs_permission() instead of having
it triggered on every step of preceding pathname resolution.  LOOKUP_CHDIR
is killed by that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 3 deletions

diff --git a/fs/open.c b/fs/open.c
index b2e4c93..8e02d42 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -501,12 +501,11 @@ asmlinkage long sys_chdir(const char __user * filename)
 	struct nameidata nd;
 	int error;
 
-	error = __user_walk(filename,
-			    LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
+	error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
 	if (error)
 		goto out;
 
-	error = vfs_permission(&nd, MAY_EXEC);
+	error = vfs_permission(&nd, MAY_EXEC | MAY_CHDIR);
 	if (error)
 		goto dput_and_out;